The Collaborative International Dictionary of English v.0.48:

Miterwort \Mi"ter*wort`\, n. (Bot.)
   Any plant of the genus Mitella, -- slender, perennial herbs
   with a pod slightly resembling a bishop's miter; bishop's
   cap.
   [1913 Webster]

   False miterwort, a white-flowered perennial herb of the
      United States (Tiarella cardifolia).
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

mitrewort \mitrewort\ n.
   Any of various rhizomatous perennial herbs of the genus
   Mitella having a capsule resembling a bishop's miter. [Also
   spelled miterwort.]

   Syn: miterwort, bishop's cap.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

miterwort
    n 1: any of various rhizomatous perennial herbs of the genus
         Mitella having a capsule resembling a bishop's miter [syn:
         miterwort, mitrewort, bishop's cap]